Differential interference contrast and fluorescence micrographs displaying colocalization of internalized targets and fluorescent dextran.

(A,C) Differential interference contrast (DIC) images of transfectants. (B,D) Fluorescent micrographs indicating the location of the preloaded fluorescent dextran. Panels A and B show clone 131-3 (n = 3) expressing wild-type FcγRIIA. Panels C and D show clone 169-23 (n = 5), which expresses mutant tail-minus FcγRIIA and CR3. Colocalization of the fluorescent dextran (arrowheads) can be observed with the wild-type FcγRIIA but not in the clone expressing mutant tailless FcγRIIA and CR3 (169-23). Of 104 internal targets, 101 were colocalized with fluorescent dextran in wild-type FcγRIIA-transfected cells. However, tailless FcγRIIA only showed target colocalization with dextran in 3 of 41 cases (original magnification × 1100). TRITC indicates tetramethylrhodamine isothiocyanate.